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BULLETIN OF THE 

ffiPEPiEioFAiami 

No. 109 


o Contribution from the Bureau of Plant Industry, Wm. A. Taylor, 

June 11, 1914. 



THE MOLDS OF CIGARS AND THEIR PREVENTION. 

By It. H. True, 

I | 

Physiologist in Charge of Plant Physiological and Fermentation Investigations. 

INTRODUCTION. 

In 1901 a number of complaints were received from eastern cigar 
manufacturers to the effect that considerable losses were being sus¬ 
tained through the appearance of moldy growths on the finished 
products. These growths in some cases appeared within about three 
days after the manufacture and the boxing of the cigars, thus fre¬ 
quently being noticed before they left the factory. In some instances, 
however, they did not appear until after considerable periods of 
time. If the mold was detected before the cigars left the factory, the 
only recourse was to wipe off the growth by hand, a rather expensive 
process. Perhaps equally objectionable results followed when the 
mold was not discovered until the cigars were in the hands of the 
buyers. In either case very considerable loss was likely to result. 

The writer was asked to study the problem and, if practicable, to 
work out feasible means by which the trouble could be remedied. 
Several factories in which this trouble appeared were visited, mana¬ 
gers were consulted, and materials for further work were obtained. 

FACTORY CONDITIONS. 

In order to get light on the conditions to be dealt with, the proc¬ 
esses involved in making the brands of cigars most liable to mold 
were observed in the factories. In the case of one factory more diffi¬ 
culty was experienced with Sumatra wrappers than with other sorts, 
and the trouble was believed to be worse in rainy seasons than at 
other times. The mold usually appeared most abundantly on the 
“ head,” or closed end of the cigar, less frequently on the veins or 


Note. —This paper discusses the losses due to the development of molds on cigars, out¬ 
lines the studies directed toward the prevention of them, and presents practical directions 
for the use of an effective remedy. The molds were found to be introduced principally 
through the gum-tragacanth paste used to fasten the small flap at the head of the cigar. 
The sterilization of the paste by using a nearly saturated solution of boric acid instead 
of water in mixing it has proved so successful that it has become a routine process in the 
factory in cooperation with which the investigations were conducted. 

43386°—Bull. 109—14 

Monograph 



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BULLETIN 109, U. S. DEPARTMENT OF AGRICULTURE. 




other elevated portions of the wrapper, but in some cases the entire 
surface was more or less involved. 

The wrapper leaf is usually prepared for use the day before it is 
actually used in manufacture. It is first brought into the necessary 
moist condition, or gotten into “ case,” by dipping into water. The 
leaves are bound into small bundles in which the bases of the leaves 
are tied together. These bundles, or “ hands,” are grasped by their 
bases and carried down into and through the “ casing ” liquid with 
a scooping motion, so performed as to drag the bundle of leaves with 
the bases ahead, the blades of the leaves being pulled through the 
liquid. After this quick dip, the bundles are shaken and set upright 
on a draining board to permit the surplus liquid to drain away. 
The pile, loosely packed together, is then covered with a moist cloth 
and allowed to stand until the droplets of water clinging to the sur¬ 
face of the leaves have been absorbed. In a few hours the leaf be¬ 
comes soft and pliable without giving the impression of being wet. 
The ribs are then pulled out and the broad leaf blades are worked 
up as their size, shape, and quality may determine. The freshly 
made cigars are then sorted according to colors and boxed immedi¬ 
ately, or sometimes held in bundles, to be packed later. 

In this condition each cigar is round, and the prescribed number 
of cigars when placed in the box overfill it, so that the cover must be 
brought into place by the use of pressure. Here the moist cigars 
yield to each other and take on such flattened sides and angles as 
may be required to get the box closed. Sometimes the lids of the 
boxes are considerably bent by the pressure of the fresh cigars, and 
the boxes are then placed for a day in large presses before they are 
nailed up. In warm weather the mold sometimes appears while the 
boxed cigars are in the presses; that is, within 48 hours after they are 
made, but more frequently within a week or two after making. 
When warm, humid weather conditions prevail it is not rare for 
molds to appear while the cigars are in transit or in storage. Since 
heat and moisture are necessary conditions for mold development, 
it follows that little trouble is experienced in the winter months but 
much during the hot summer months. 

A number of attempts had been made by the factory managers 
to remove this source of loss. Small quantities of vinegar in the 
water (1 pint in 4 or 5 gallons) used for casing wrapper leaf were 
found to aggravate the trouble. When the leaf was cased in vinegar 
at full strength the molds were suppressed, but the luster of the 
leaf was thought to be impaired. Casing in alcoholic solutions was 
found to be helpful, but too expensive. Small quantities of glyc¬ 
erin were found to be useless in suppressing molds, but helpful in 
retaining moisture in the wrapper. 


d; of d, 

m 22 1314 


THE MOLDS OF CIGARS AND THEIR PREVENTION. 3 

LABORATORY INVESTIGATIONS. 

Cigars on which mold had developed were obtained from several 
sources and submitted to examination. Two forms of mold seemed 
to be present—one, of most common occurrence, a small organism 
of grayish or whitish appearance, usually thinly scattered over the 
cigars, but most abundant and frequent at the head of the cigar, 
and the other a larger organism, occurring usually near the head 
of the cigar in rather sharply defined patches of a dazzling white 
color. The letter organism was much less frequently seen. 

It being evident that the factories offered favorable conditions for 
retaining spores of molds when once introduced, it was clear that 
general treatment looking toward the eradication of these organisms 
was out of the question, assuming that it was practicable to prevent 
the entrance of new infections on tobacco leaf and other materials 
brought in. The most serious localized sources of trouble were there¬ 
fore sought. 

PASTE USED. 

Gum tragacanth is used in small quantity to fasten the wrapper 
of the cigar in place. The wrapper is rolled tightly on the cigar, 
the rolling proceeding from the open end toward the head, the last 
portion of the wrapper remaining free being a small flap of leaf 
which serves to finish off the head. This small flap receives a little 
paste on the under surface and is then carefully brought into place. 
The cigar is then usually rolled with some pressure between the 
•hand and the board or table at which the cigar maker works, thus 
giving it the desired regularity of form. Thus, a little paste is 
always found at the head of the cigar, and if an excess has been 
applied, especially if the paste is rather thin, a portion is liable to 
be squeezed out on to the board or table at which the maker works, 
and the cigars may receive a more or less extensive smear of paste 
over the surface of the wrapper. 

The paste as usually made up contains about 10 parts by weight . 
of gum tragacanth to 90 parts of water. A large stock is gener¬ 
ally made in one container, sometimes only enough to last for the 
day and sometimes enough to last for a longer period. An in¬ 
spection of the paste pots in several factories showed that while 
some were in fairly clean condition the sides of others were thor¬ 
oughly covered with molds, indicating that in some cases little 
attention was paid to cleanliness regarding this feature. 

An inspection of the wrapper leaf in no case showed visible mold, 
although it is a matter of common observation that when tobacco 
leaves are kept sufficiently moist in a closed space they can be made 
to mold. 



4 


BULLETIN 109, U. S. DEPARTMENT OF AGRICULTURE. 


MOLDS IN TRAGACANTH GUM. 

Tragacanth gum is usually bought in considerable quantities for use 
in the larger factories, and, if the samples obtained in this investiga¬ 
tion from several such sources were representative, the highest grades 
of the gum are not used. It was thought possible that these gums 
themselves might be carriers of molds, and several samples were set 
away in sterile Petri dishes to which a small quantity of sterile dis¬ 
tilled water was added. These cultures, like others to be described, 
when not under observation were kept in a dark chamber in which 
the temperature varied between 21.5° and 25° C. In three days all 
the samples showed an abundant growth of molds, which began to 
develop fruiting stages on the fourth day. For further study, cul¬ 
tures were transferred to a medium containing one-half of 1 per cent 
sodium chlorid, 1 per cent peptone, 1 per cent beef broth, and +10 
points acidity. Other cultures were also prepared on sterilized 
tragacanth gum, partly prepared on a thick paste and partly on a 
thinner paste. 

Cultures on beef agar and peptone flourished and yielded a variety 
of organisms, which were turned over for identification to Mrs. Flora 
W. Patterson, Mycologist of the Bureau of Plant Industry. Four 
forms appeared with great regularity. Most conspicuous and quick¬ 
est in growth were (1) Rhizoporus nigricans Ehren., a large organ¬ 
ism forming large, loose, conspicuous hyphal masses; (2) Mucor 
racemosus Fres. var. brunneus Morini, a smaller organism rapidly 
forming a loose, white mass of hyphse; and (3) Penicillium sp., a 
somewhat slower organism in point of development, marked by its 
white round-headed conidiophores. This organism in the early 
stages was striking by reason of its brilliant whiteness, but as the 
cultures grew older the more usual bluish color appeared. The last 
common form was (4) Aspergillus candidus Link, a very small mold, 
characterized by its slower growth, its dingy white color, and its 
appearance in mixed cultures as a minute undergrowth among the 
above-mentioned larger organisms. No attempt was made to carry 
out a further study of these organisms. It seemed clear, however, 
that the Aspergillus was more at home on the tragacanth medium 
than on the beef agar and peptone as here offered. 

MOLDS ON WRAPPER LEAF. 

As it seemed very probable that the wrapper leaves, like most 
other free surfaces, might give lodgment to spores of molds and 
thus become agents of infection, it was thought desirable to see what 
molds could be cultivated from them. Accordingly, cultures in the 
media previously described were prepared from the washings ob¬ 
tained by rinsing the surfaces of wrapper leaves with sterile water. 
Several organisms were obtained in small quantities, and Mrs. Pat- 


THE MOLDS OF CIGARS AND THEIR PREVENTION. 


5 


terson identified the following: (1) Aspergillus subgriseus Pk., (2) 
Macrosporium commune Rabh., (3) Sterigmatocystis castanea Pat¬ 
ters., (4) Cladosporium herb arum (P.) Link, (5) Penicillium sp. 
In general, the leaf surfaces were rather sterile of molds. 

MOLDS ON CIGARS. 

Samples of moldy cigars obtained from various sources were also 
investigated by the method described, and the following organisms 
were identified by Mrs. Patterson: (1) Aspergillus candidus Link, a 
very small dingy white mold, occurring as a rather sparse growth 
on cigars, especially near the head, but frequently in diffuse growth 
over a considerable part of the surface, which seems to be the most 
often present on cigars and is probably responsible for most of the 
trouble; (2) Penicillium sp., a widely distributed mold, likely to 
appear on a great variety of substances; (3) Sterigmatocystis 
castanea Patters., an unusual form, not likely to be a cause of harm 
here; (4) Cladosporium herbarum (P.) Link, one of the molds com¬ 
monly turning up on decaying vegetable matter, probably not a 
source of serious trouble here. 

It will be seen that the organisms responsible for the most serious 
trouble ( Aspergillus candidus , easily first in importance, and Peni¬ 
cillium glaucum ) are not represented in the list of organisms in¬ 
troduced on the wrapper leaf, but seem to be always present in the 
tragacantli gum. The conclusion seems, therefore, to follow that 
in the case in hand the paste used in fastening the wrapper at the 
head of the cigar brought with it the troublesome organisms. 

INFECTION EXPERIMENTS ON WRAPPER LEAF. 

It having been rendered probable that the tragacantli paste was 
inoculated with the molds from the start, the next question to be 
answered was that of the seat of the growth of molds on the wrap¬ 
pers. As it has already been shown that the paste itself is a favorable 
culture medium for these organisms, it follows that the tobacco leaf 
in itself is not necessarily a favorable support for the molds. How¬ 
ever, it is well known that moist tobacco leaves do become moldy 
under conditions favoring this process, and experiments were made 
having for their object the infection of wrapper leaves with the two 
species of mold last mentioned. These attempts failed to produce 
mold on the leaves used in the absence of any substance foreign to 
the leaves that might act as a source of food for the fungi. 

INFECTION EXPERIMENTS ON CIGARS. 

In view of the nature of the problem under study, the fact that 
cigars could be infected with molds was not open to doubt. Since 
it had been shown that these molds do not readily grow on wrapper 


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BULLETIN 109, U. S. DEPARTMENT OF AGRICULTURE. 


leaf, it appeared probable, in view of the fact that the infection 
was introduced with the tragacanth paste, that the growth on the 
cigar was confined to the paste present on the wrapper. It was 
thought desirable to try to check up this conclusion by attempting 
to grow these molds on cigars. Accordingly, repeated attempts were 
made to grow the organisms in question on pieces of cigars moistened 
and placed in sterile Petri dishes or test tubes. In some cases these 
pieces molded and in others they did not. Usually the piece at the 
head of the cigar molded without difficulty, while those portions from 
other parts of the cigar molded less readily. 

This seemed to confirm the view that the molds were introduced 
with and in general grew on the paste, and the appearance of the 
mold over a large part of the surface of a cigar indicated the smear¬ 
ing of excess paste- over a corresponding portion of the surface. 

REMEDIAL MEASURES. 

Having located the cause of the trouble in the organisms above 
discussed and having found the point of their entrance, as well as 
the seat of their activities, to be in the tragacanth paste, practical 
remedial measures seemed to lie along the line of sterilizing the 
paste. 

In view of the conditions governing the subsequent handling and 
final utilization of cigars, an acceptable sterilizing agency must 
combine several characteristics. It must be permanent, since cigars 
sterilized for but a short time are liable to mold at a later period 
when conditions of heat and moisture concur with or follow the 
exposure of the cigars to the infecting organisms. The substance 
must be odorless and tasteless; otherwise it will alter the taste and 
aroma of the cigar, points on which smokers, and therefore dealers, 
are very sensitive. It must not alter the color or the luster of the 
wrapper, since on these the selling quality of the cigars in consider¬ 
able part depends. 

STERILIZATION OF THE PASTE. 

A variety of substances having antiseptic properties were chosen 
for test. In general they were dissolved in water, and the resulting 
solutions were either added to the paste already made or were used 
instead of water in making up the paste. These pastes were then 
inoculated with the molds obtained from the moldy cigars or from 
tragacanth gum. 

A thin paste containing 10 grams of gum in 1 liter of water was 
first used. Hydroquinone, thymol, and sodium salicylate were intro¬ 
duced in concentrations as strong as could be used without influ¬ 
encing in an objectionable degree the taste, color, or odor. These 
pastes were then inoculated with Aspergillus candidus and Peni- 
cillium glaueum. In all cultures except that containing 5 c. c. of 


THE MOLDS OF CIGARS AND THEIR PREVENTION. 7 

^molecular solution of hydroquinone in 100 c. c. of paste, both molds 
appeared and throve. 

I A thicker paste, containing 10 grams of gum in 250 c. c. of distilled 
water, was made and a series of cultures prepared to which hydro¬ 
quinone, thymol, and boric acid were added. Inoculation with the 
same molds followed. Hydroquinone in permissible concentration 
failed to suppress the organisms. Thymol in saturated solution, 1 
c. c. and 3 c. c. per 100 c. c. of paste, suppressed them, but gave so 
marked an odor of thymol that the use of this substance was re¬ 
garded as not advisable. Boric acid, 1 c. c. to 10 c. c. of saturated 
solution in 100 c. c. of paste, failed to suppress the- organisms. 
Indeed, both grew more luxuriantly in these cultures than in the 
cultures containing simple paste. Cultures containing about 0.12 
gram of dry boric acid in 100 c. c. of paste remained sterile. 

In a third series of tests, solutions of the disinfectants were used 
instead of water in making the pastes. Solutions of hydroquinone 
and of boric acid were used in several proportions, as follows: For 
1 gram of dry gum 25 c. c. of solution were used, consisting, re¬ 
spectively, of hydroquinone in molecular, one-half molecular, and 
one-fourth molecular concentration and boric acid in saturated solu¬ 
tion at room temperature and in one-half saturated concentration. 
Since at 60° F. 1 part of boric acid dissolves in 26 parts by weight of 
water, it will be seen that the stronger boric-acid solution used in¬ 
stead of water in making the paste contained roughly 3.8 per cent 
of the acid. The paste cultures when made up were decidedly stiff 
and kept the form of small cakes in the Petri dishes. These cakes 
were inoculated with the two molds, and the cultures containing 
hydroquinone and the more concentrated boric-acid solution re¬ 
mained sterile. The culture containing the one-half normal boric- 
acid solution proved a more favorable medium for these molds than 
the plain paste. 

It was rendered clear by these experiments that hydroquinone is 
effective when a solution containing 2.7 grams in 100 c. c. of solu¬ 
tion is used instead of water in making the paste. Likewise, when 
a solution containing roughly 3.8 grams of boric acid in 100 c. c. 
of solution is similarly used molds are^suppressed. 

Tests of the adhesive quality of the pastes so prepared were made 
and it was conclusively shown that the presence of these chemical 
substances does not decrease the value of the paste in this particular. 

After considering which of these substances should be recom¬ 
mended for general use, boric acid was chosen because it is cheaper, 
does not undergo change in the paste, is more readily obtained, and 
is not liable to injure anybody if used in excess. The disadvantages 
of hydroquinone lie in its contrasted properties on the points enu¬ 
merated. 


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RARY OF CONGRESS 



0 015 793 292 


8 


BULLETIN 109, U. S. DEPARTMENT OF ^AGRICULTURE. 
PRACTICAL DIRECTIONS FOR THE USE OF THE REMEDY. 


A practical course of treatment based on the use of boric acid 
was accordingly outlined for tests on the factory basis. Since the 
paste evaporates water between the time of making and of using, a 
concentration somewhat less than saturation was recommended in 
making the paste. This would also tend to decrease the liability of 
the acid to crystallize out in a conspicuous way on the surface of 
the cigars should paste happen to be smeared on them. The fol¬ 
lowing concise directions were prepared: Place boric acid in warm 
water at the rate of 1 ounce of dry acid to If pints of water. Stir 
till the acid is all dissolved. Use this solution instead of water in 
making up the paste. Great care should be taken not to use more 
paste on the cigar than is necessary, since it is liable to be smeared 
on the surface of the cigar, where the boric acid in the paste tends 
to crystallize, giving an appearance suggesting mold. 

These directions have been followed for some years in the fac¬ 
tory in which the complaints originated, and when the writer was 
last in communication with those in charge the boric-acid treat¬ 
ment was in use as a routine practice and only in rare instances 
were molds found troublesome. 


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WASHINGTON : GOVERNMENT PRINTING OFFICE : 1914 

































































































































































